C++ STL Map vs Vector speed

Question

In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, fu

Answer 1

A map is a good thing to use for a symbol table. but operator[] for maps is not. In general, unless you are writing some trivial code, you should use the map's member functions insert() and find() instead of operator[]. The semantics of operator[] are somewhat complicated, and almost certainly don't do what you want if the symbol you are looking for is not in the map.

As for the choice between map and unordered_map, the difference in performance is highly unlikely to be significant when implementing a simple interpretive language. If you use map, you are guaranteed it will be supported by all current Standard C++ implementations.